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# Convert a given surface mesh to volume mesh (FVM)

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### Convert a given surface mesh to volume mesh (FVM)

Posted by Ashish Kumar at February 20. 2018

I have multiple intersecting planes in a 2D mesh, and I want to convert that to a volume mesh by extruding along the surface normals. But I am facing problem at the intersection points.

The following links show different figures related to

2) surface mesh extruded https://www.dropbox.com/s/mtedk7me62sbloy/surfaceMeshExtruded.PNG?dl=0

3) Target mesh (This shows how the mesh should look like at the intersection point) https://www.dropbox.com/s/rpqn355za4p4pvl/volumeMeshSketch.jpg?dl=0

Please let me know if there is some way to create this type of surface mesh to volume mesh to be used in a finite volume simulations.

### Re: Convert a given surface mesh to volume mesh (FVM)

Posted by Saint Michael at February 20. 2018

Hi

Try the following

1) Import 2D mesh in Geometry module (via STL format),   Remove Extra Edges

2) Add thickness to each plane

3) Make Partition of thickened planes.

4) Make hexahedral meshing.

St.Michael

### Re: Convert a given surface mesh to volume mesh (FVM)

Posted by Ashish Kumar at February 22. 2018

Thanks for your reply. I understand the process. But when I am trying to remove extra edges from STL in geometry module, it does not do anything. The number of edges remains same as in STL.

And, How to add thickness to the planes? I could not find that option.

Previously Saint Michael wrote:

Hi

Try the following

1) Import 2D mesh in Geometry module (via STL format),   Remove Extra Edges

2) Add thickness to each plane

3) Make Partition of thickened planes.

4) Make hexahedral meshing.

St.Michael

### Re: Convert a given surface mesh to volume mesh (FVM)

Posted by Saint Michael at February 22. 2018

But when I am trying to remove extra edges from STL in geometry module, it does not do anything.

Switch on "Union faces, laying ..." option

How to add thickness to the planes?

New Entity > Generation > Thickness

St.Michael

### Re: Convert a given surface mesh to volume mesh (FVM)

Posted by Ashish Kumar at February 22. 2018

I had tried switching the "Union faces, laying ..." option and it did not help. I think there may be some problem with the STL file being generated from the mesh module.

And I tried New Entity > Generation > Thickness, but it is not allowing me to select the stl file.

I have uploaded my hdf file in the following link. Can you please check what I am doing wrong.

Thanks

Ashish

### Re: Convert a given surface mesh to volume mesh (FVM)

Posted by Saint Michael at February 22. 2018

### Re: Convert a given surface mesh to volume mesh (FVM)

Posted by Ashish Kumar at February 22. 2018

Thanks. But This is not what I want. I want to generate two different FVM meshes. One for the "Res" domain and one for the "crack" domain. Res domain mesh will have crack faces in the generated mesh. And then I want to generate crack domain volume mesh which is conforming to the crack faces in the Res domain.

The study file I sent you, had generated the Res domain mesh successfully. Then I extracted crack faces in the Res mesh and I wanted to generate crack domain volume mesh using crack faces.

Were you able to identify why "remove extra edges" did not work for the crack stl file and also adding thickness part.  I think if I can do these two then I will achieve my meshing objective.

Thanks

Ashish

Previously Saint Michael wrote:

Here is the result study

St.Michael

### Re: Convert a given surface mesh to volume mesh (FVM)

Posted by Saint Michael at February 22. 2018

Sub-mesh_3 in the sent study is not it what you need?

St.Michael

### Re: Convert a given surface mesh to volume mesh (FVM)

Posted by Ashish Kumar at February 22. 2018

I am sorry, I did not look into the submesh section. This is exactly I want. Thank you very much for the help.

### Re: Convert a given surface mesh to volume mesh (FVM)

Posted by Ashish Kumar at February 23. 2018

Hi Michael,

I am trying to create more complex cases. The crack planes can be intersecting at any arbitrary angle as shown in this figure

https://www.dropbox.com/s/8v4vjv3iox4vg8g/dippingCrack.PNG?dl=0

In this complex case, I think I will have to use tetrahedral mesh. I got success in creating the Res domain mesh correctly. Now I want to create the "crack" domain mesh which should be conforming with the crack faces in the Res mesh. I tried extruding the crack faces but there are problems at the intersection point.

Can you please look into my case and suggest some way to create crack domain volume mesh. The study files are located in this folder https://www.dropbox.com/sh/e8j9952ujyu9ut1/AABdmj5ArDho0Khw1rUSTAfYa?dl=0

Thanks a lot for your help.

### Re: Convert a given surface mesh to volume mesh (FVM)

Posted by Saint Michael at February 26. 2018

Hi Ashish

I don't understand what is wring in this case. The mesh looks OK.

St.Michael

### Re: Convert a given surface mesh to volume mesh (FVM)

Posted by Ashish Kumar at February 27. 2018
•There should be cell (volume) at the intersection
•Let’s call the cell at intersection as “junction cell”

•“junction cell” should connect the cells from the branches such that there is a common face between junction cell and neighboring cell

Attachments

### Re: Convert a given surface mesh to volume mesh (FVM)

Posted by Saint Michael at February 27. 2018

From this point of view Mesh_2 in your study is fully correct.

St.Michael

### Re: Convert a given surface mesh to volume mesh (FVM)

Posted by Ashish Kumar at February 27. 2018

Yes, you are right. Mesh_2 is correct, but this mesh is not conforming to the crack Faces in Mesh_1 (Res Domain).

For my problem, I need Crack domain mesh to be conforming with Res domain mesh. I am trying to achieve this by creating a Res domain mesh such that it has crack Faces in it. Then use crack Faces to create a volume mesh for Crack domain.

Can you please suggest some way to achieve this.

Thanks

Ashish

### Re: Convert a given surface mesh to volume mesh (FVM)

Posted by Saint Michael at February 27. 2018

What you mean saying "conforming" here?

St.Michael

### Re: Convert a given surface mesh to volume mesh (FVM)

Posted by Ashish Kumar at February 27. 2018

By conforming I mean crack Face mesh should exactly match the faces in the crack volume mesh.